200 Effect of Chemicals. 



is no longer resistant to decomposition through bacterial con- 

 tamination, after the hepin has been added. 



2. Years ago von Behring recommended the preservation 

 of milk by formaldehyde. Experiments upon animals showed that 

 the addition of formaldehyde to milk in the proportion of 1 :1250 

 gave it no properties injurious to health by any method of appli- 

 cation (even intravenously), and it was further found that animals 

 with a very delicate sense of smell failed to recognize the presence 

 of formaldehyde if it had been added to the milk in a dilution 

 of 1 :10,000. The action of formaldehyde in such dilution is quite 

 marked. The addition of a 1 :10,000 dilution postpones coagulation 

 for many days (von Behring, Price and Schaps) ; 1:25,000 and 

 1:40,000 prevents coagulation from 1 to 4 days (Kolle). The 

 action of formaldehyde was found to be more effective in accord- 

 ance with the cleanliness of the natural milk and this action ac- 

 cording to Rothschild and Metter appears to result from the fact 

 that the lactic acid bacilli chiefly succumb, whereas the other 

 saprophytes are harmed to a lesser degree. Tubercle bacilli are 

 not influenced in their viability by these dilutions. 



The feeding of infants for weeks with formalin milk (addi- 

 tions of 1 :25,000) may result in an injury of the kidney epithelium 

 of the children, which leads to the elimination of albumin. Ac- 

 cording to Baudini the rennet pepsin and trypsin action may be 

 considerably inhibited by formalin; the acidity of the milk is 

 increased. In the experiments of von Behring the action of 

 formalin depends upon its effect in checking the development of 

 bacteria, and not on its disinfecting or sterilizing property. A 

 concentration of 1 :25,000 up to 1 :50,000 has no influence on the 

 typhoid and colon bacteria and staphylococci (Vaughan and 

 Schaps). Diphtheria, colon and pyocyaneus bacilli have not been 

 destroyed even in dilutions as low as 1 :5,000. Tubercle bacilli are 

 protected by their waxy covering even against higher proportions 

 of formalin, and as a matter of fact formalin is used, on account 

 of its action on other bacteria, for the purification of sputum for 

 the purpose of cultivating the tubercle bacilli from the saliva. 

 Formalin milk constitutes a food which should be designated as 

 spoiled and injurious to health. 



3. Seiffert worked out a method of milk preservation in 

 which the bactericidal action of ultra-violet rays is used for 

 sterilization of milk. The method of action of the ultra-violet rays 

 has not yet been satisfactorily explained. According to Lobeck 

 (cited by Grimmer) the exposure of water to such rays produces 

 peroxide of hydrogen. Grimmer believes that the latter is also 

 formed in milk, but on account of the catalectic factors of the milk 

 it immediately decomposes again. It is possible that the forma- 

 tion of peroxide of hydrogen constitutes the germicidal power of 

 ultra-violet rays. The milk fat is not changed (Lobeck). Ac- 

 cording to Dreier-Hansen the proteid is coagulated after a pro- 



